This Phase 2b study of peficitinib (ASP015K), an orally administered once-daily JAK inhibitor, plus MTX, demonstrated efficacy across multiple secondary endpoints with higher peficitinib doses. Peficitinib in combination with MTX was well tolerated with a safety profile that was consistent with previous studies.A high placebo response rate was seen in both Latin and North America, when patient data were stratified. This high placebo rate is problematic for the accurate interpretation of peficit...